Proteases are enzymes capable of cleaving peptide bonds. Acid proteases (e.g., proteases having an acidic pH optimum) are produced by a number of different organisms including mammals and microbes. For instance, microbial acid proteases are produced by bacterial strains such as strains of Bacillus sp. (JP 01240184) and fungal strains, such as strains of Rhizopus sp. (EP 72978), Schytalidium sp. (JP 48091273), Sulpholobus sp., Thermoplasma sp. (WO/90 10072) and Aspergillus sp. (JP 50121486 and EP 82 395).
Berka et al. (Gene (1990) 96:313) disclose a gene encoding the aspartic proteinase aspergillopepsin A from Aspergillus awamori. The cloning of a gene encoding the aspartic proteinase aspergillopepsin O from Aspergillus oryzae is described by Berka et al. (Gene (1993) 125:195-198). The cloning of a gene encoding the acid protease (PepA) from Aspergillus oryzae is disclosed by Gomi et al. (Biosci. Biotech. Biochem. (1993) 57(7):1095-1100).
Proteases and particularly acid proteases are widely used in industrial applications, e.g., in the preparation of food and feed, in the leather industry (e.g., to dehair hides), in the production of protein hydrolysates, and in the production of alcohols, such as ethanol production, wine production and brewing.
Yet, there is a continuing need for proteases for many different applications, especially in the food and feed industry.